JPH07244198A - Compact of buffer gent for geologic disposal of radioactive pollutant - Google Patents

Abstract

PURPOSE:To improve the airtightness in the juncture and relieve the labor in installing a buffer agent by forming an internal thread component on the inner surface of the opening of a housing hole in a main body and an external thread in a lid and screwing the lid on the main body. CONSTITUTION:A compact 10 of a buffer agent consists of a main body 11 and a lid 12. The main body 11 shaped like a cylinder with a base has a housing hole 11a which is made a little larger than a radioactive pollutant containment to be disposed of in a stratum and an internal thread component 11b which is made on the inner surface of the opening of the housing hole 11a. The lid 12 consists of a disk component 12a, an interlocking projection 12b and an external thread 12c made around it. Compacts of these buffer agents are manufactured at a plant by compressively molding powdery molded buffer agents such as bentonite, and are buried in a disposal hole in a tunnel; the main body 11 is loaded into the disposal hole and the pollutant containment is housed in a housing hole 11a of it to seal up pollutants without fail by screwing the internal and external thread components while turning the lid 21 as well as through the swelling of a buffer caused by moisture absorption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushioning material molding for geological disposal of radioactive contaminants.

[0002]

2. Description of the Related Art Radioactive contaminants (radioactive waste liquid, radioactive waste, spent fuel, etc.) with high, medium and low radioactivity levels are classified by radioactivity level (high, medium and low) and It is stored in a dedicated sealed container corresponding to the above, and is stored, stored, and disposed of in the stratum.

As a related technique for accommodating radioactive contaminants in a deep underground and isolating them from the living sphere, Japanese Patent Application Laid-Open No. HEI 2-
No. 236500, "Method for producing buffer material for radioactive waste disposal", and JP-A-5-150097, "Method for geological disposal of radioactive material storage body and geological disposal body" have been proposed.

In the former technique, a powder made of bentonite or the like is compressed and solidified into a high-density state by a cold isostatic press or the like to form a block-shaped molded body, which is carried into a geological disposal site to be in a vitrified state. The solidified body (radioactive contaminant storage body) such as the above is embedded so as to be surrounded by a block-shaped cushioning material. In the latter technique, as shown in FIG. 5, a bedrock (host rock) 1 is excavated to open a disposal hole 2, and a radioactive substance container (radioactive pollutant) is collected by cold isostatic pressing or the like. (Houses A) A high-density buffer layer 5H is formed around the geological disposal body C, and the geological disposal body C is loaded into the disposal hole 2 to form a fine-grained bentonite in the gap G. The buffer material is buried by being filled with the buffer material, the disposal hole 2 is covered with a lid 6, and the lid 6 is fixed to the bedrock 1 with anchor bolts 7. Reference numeral 8 in the drawing is a tunnel.

[0005]

However, according to the former technique, since the cushioning material is in the form of a block, a large amount of it is manufactured in a factory or the like, and then carried to the disposal site. Although it has the advantage that the geological disposal work can be carried out easily, it is necessary to stack multiple block-shaped cushioning materials around the radioactive contaminant storage body, so a gap is formed in the stacked part. It is easy, and there are some places where the water permeability is impaired by the number of blocks, which is disadvantageous in preventing the permeation of groundwater. The latter technique is suitable for lowering water permeability and preventing water from entering the radioactive contaminant container A, but the high-density buffer layer 5
Due to the brittleness of H and the heavy weight of the geological repository C, the geological repository C in which the radioactive contaminant container A is covered with the high-density buffer layer 5H is carried from the ground to the tunnel 8 and the disposal hole 2. In addition, at the time of loading, the high-density buffer layer 5H is likely to be damaged, and the handleability is poor and the workability is likely to deteriorate.

The present invention has been made in view of the above circumstances, and it is possible to reduce the generation of a gap at a joint portion to improve the hermeticity and to reduce the labor at the time of installing a cushioning material in a disposal hole. It is an object.

[0007]

[Means for Solving the Problems] As a cushioning material for burying a radioactive contaminant container in a sealed state, powder of bentonite or the like is formed by compression and solidification in a high density state by a cold isostatic press or the like. In addition to the combination of the body and the lid, the body has a storage hole for loading the radioactive contaminant storage body that is to be geologically disposed, and the concavo-convex engaging portion is provided at the joint between the body and the lid. To be done. The body is formed into a bottomed cylindrical body. The concavo-convex engaging portion includes a female screw portion formed on the inner peripheral surface of the opening of the housing hole in the body, and a male screw portion formed on the lid that closes the opening of the housing hole and screwed into the female screw portion. Are arranged. The concavo-convex engaging portion is additionally provided with a configuration having an annular disc-shaped joint surface and a taper-shaped joint surface in a connected state with the disc-shaped joint surface. Further, an annular disc-shaped joint surface and a cylindrical joint surface in a connected state to the disc-shaped joint surface are selectively added to the concave-convex engaging portion.

[0008]

[Function] The cushioning material molded body for geological disposal of radioactive pollutants is manufactured on the ground and transported to the required location of the geological disposal site.
A radioactive contaminants storage body is inserted into the storage hole of the main body and closed. At this time, if the concave-convex engaging portion is arranged at the joint portion between the body and the lid, the flow path is bent to increase the sealing distance at the joint portion, and the resistance against water intrusion increases. When the trunk body is in the shape of a cylinder with a bottom, the storage hole is surrounded by the peripheral wall except for the joint portion to prevent water from entering.
When the concave-convex engaging portion is in a screwed state by the female screw portion and the male screw portion, the storage hole of the body is closed by the rotation operation of the lid body, and the small gap left in the screwed portion is small when water enters. Due to the swelling of the cushioning material accompanying the absorption of water, it becomes water-impervious. When the concavo-convex engagement part has a disc-shaped joint surface and a taper-shaped joint surface, the weight of the lid body is added to the taper-shaped joint surface when the body body and the lid body are combined, so that they are in close contact with each other. In this state, airtightness is generated, and the disc-shaped joint surfaces come into contact with each other, whereby the lowering of the lid body is suppressed and the load is supported. When the concavo-convex engagement part has a disc-shaped joint surface and a cylindrical joint surface, in addition to restraining the lowering of the lid and supporting the load, radial movement due to contact of the cylindrical joint surface Suppression and position setting are done.

[0009]

[Embodiment] A first embodiment of the buffer material molded body for geological disposal of radioactive contaminants according to the present invention will be described below with reference to FIGS. 1 and 2. In FIGS. 1 and 2, reference numeral 10 is a cushioning material molded body (molded body) for geological disposal of radioactive contaminants, 11 is a body, 11a is a receiving hole, 11b is an internal thread portion, 12 is a lid body, and 12a is a disk portion. , 12b are engaging protrusions, 12c is a male screw portion, 13 is a concave-convex engaging portion, and 14 is a disc-shaped joining surface.

As shown in FIGS. 1 and 2, the molded body 10 is a combination of a body 11 and a lid 12, each of which is formed by cold isostatic pressing of powder such as bentonite. And the like, so as to be compressed and solidified in a high-density state to be molded.

In the example of FIG. 1, the body 11 is formed in a cylindrical shape with a bottom, and is a cylindrical storage hole having a shape slightly larger than the final shape of the radioactive contaminant storage body A for geological disposal. 11a and one or a plurality of female threaded portions 11b formed on the inner peripheral surface of the opening of the accommodation hole 11a.

The lid 12 has a disc portion 12a, an engagement protrusion 12b arranged at the center of the disc portion 12a and inserted into an upper opening of the storage hole 11a, and an integral body around the engagement protrusion 12b. Storage hole 11 for body 11 formed by molding or the like
It has a threaded portion 12c for screwing into a.

The concavo-convex engaging portion 13 is arranged at the joint between the body 11 and the lid 12. In the example of FIGS. 1 and 2, a disc-shaped joining surface 14 with the upper end surface of the body 11 and the lower surface of the disk portion 12a, and the screw portions 11 located below the disk-shaped joining surface 14 are joined together.
b, 12c.

The body 11 of the molded body 10
The lid 12 and the lid 12 are molded by a cold isostatic press or the like using a powdered cushioning material such as bentonite, etc. in a place where a working environment such as a factory on the ground is secured.
It is carried in together with the radioactive contaminant container A into the tunnel 8 described in 1. and buried in the disposal hole 2.

The body 11 is loaded into the disposal hole 2 and the radioactive contaminant storage A is stored in the storage hole 11a, and the lid 12 is inserted.
By screwing the female screw portion 11b and the male screw portion 12c with each other while rotating, the radioactive contaminant container A is sealed.

When the two threaded portions 11b, 12c are screwed together, as shown in FIG. 2, the screw threads come into close contact with each other and the disc-shaped joint surface 14 comes into close contact with each other.

When water such as groundwater enters the periphery of the molded body 10 in the buried state of the radioactive contaminant container A, the buffer material forming the body 11 and the lid 12 absorbs water. Occasionally, it swells to prevent the passage of water, but in addition to this action, because the body 11 has a bottomed cylindrical shape, water is blocked by the peripheral wall and the water level of the concave-convex engaging portion 13 increases. While rising to the position, it does not directly reach the storage hole 11a.

When water tries to enter from the concave-convex engaging portion 13 between the body 11 and the lid 12, the concave-convex engaging portion 13 is bent and the disc-shaped joint surface 14 is in a close contact state. And the presence of the threaded portion between the female threaded portion 11b and the male threaded portion 12c prevent water from invading in multiple layers. When the disc-shaped joint surface 14 is in a close contact state, the cushioning material swells due to contact with water, and the gap between the disc-shaped joint surfaces 14 is blocked to ensure hermeticity. When the water reaches the threaded portion between the female threaded portion 11b and the male threaded portion 12c via the gap of the disc-shaped joint surface 14, the threaded portion is in a small uneven state, so that the cushioning material is quickly By swelling with water and closing the small gap in the screwed portion, the airtightness is secured.

FIG. 3 shows a second embodiment of the buffer material molded body for radioactive contaminant geological disposal according to the present invention, in which the concavo-convex engaging portion 13 and the circular disc-shaped joint surface 14 are formed. , The tapered joint surface 15 disposed inside the disc-shaped joint surface 14 and having the inner side lowered. With such a concavo-convex engaging portion 13, the weight of the lid body 12 is added to the taper-shaped joint surface 15 when the lid body 12 is covered with the trunk main body 11 to be in a close contact state, and the sealing performance is improved, and at the same time, the lid body is covered. The body 12 is guided to the central position. When water enters the concave-convex engaging portion 13, the flow path bends and the resistance increases, and the water enters the storage hole 11a based on the close contact state of the tapered joint surface 15. Suppress. When the disc-shaped joint surfaces 14 come into contact with each other,
The load of the lid 12 is supported by this portion.

FIG. 4 shows a third embodiment of the buffer material molding for radioactive contaminant geological disposal according to the present invention, in which the concavo-convex engaging portion 13 is a circular disc-shaped joint surface 14, It is configured by combining a plurality of cylindrical joint surfaces 16 disposed inside the disc-shaped joint surface 14. Then, the lid 12 is attached to the body 11
When each disc-shaped joint surface 14 is brought into close contact with each other, the weight is supported and sealed, and the cylindrical joint surfaces 16 suppress movement in the radial direction. In addition to the setting of the position, the increase in the number of bends enhances the resistance against water intrusion.

[Other Embodiments] The following technology can be adopted for the cushioning material molding for radioactive contamination geological disposal according to the present invention. a) The concave-convex engaging portion 13 has a shape in which the inner position is higher than the outer position. b) The disc-shaped joint surface 14, the taper-shaped joint surface 15 and the cylindrical joint surface 16 are mutually combined so that the taper-shaped joint surface 15 and the cylindrical joint surface 1 are provided between the inner and outer disc-shaped joint surfaces 14.
It should have a structure in which 6 is interposed.

[0022]

EFFECTS OF THE INVENTION The cushioning material molding for radioactive contamination geological disposal according to the present invention has the following effects. (1) By combining a body and a lid body formed by compression-molding a cushioning material and arranging a concave-convex engagement portion at the joint portion, when water enters when the radioactive contaminant storage body is buried,
By bending the flow path, it is possible to increase the distance of the seal portion and suppress the invasion of water to the radioactive contaminant container together with the swelling property of the cushioning material. (2) By making the body of the cylinder to have a bottomed cylindrical shape, the peripheral wall prevents direct insertion of water at the time of intrusion of water, and compared with the case where the cushioning material is formed into a block shape, the joint portion and the gap are formed. It is possible to reduce the number of slags formed and increase the water impermeability. (3) By separately carrying the molded body and the radioactive contaminant storage body, it is possible to improve the handling property and the transfer workability. (4) By disposing the threaded portion on the concave-convex engaging portion, the work of closing the body of the body by the lid is facilitated, and at the time of entry of water in the embedded state, the sealing property of the threaded portion of the screw portion,
It is possible to obtain water impermeability by promptly swelling and blocking small irregularities. (5) By disposing the tapered joint surface in the concave-convex engaging portion, the weight of the lid body can be added to the tapered joint surface, and the lid body can be easily brought into a close contact state to enhance the hermeticity. (6) Due to the tapered joint surface, the lid body can be guided around the lid body and the accurate alignment when the lid body and the body are assembled. (7) By disposing the disc-shaped joint surface and the cylindrical joint surface, it is possible to easily support the weight of the lid body and to accurately set the position in the radial direction.

[Brief description of drawings]

FIG. 1 is a perspective view in a separated state showing a first embodiment of a cushioning material molded body for radioactive contamination geological disposal according to the present invention.

2 is an enlarged front sectional view of a part of the concave-convex engaging portion of FIG. 1. FIG.

FIG. 3 is an enlarged front sectional view showing a second embodiment of the concave-convex engaging portion in the buffer material molding for radioactive contaminant geological disposal according to the present invention.

FIG. 4 is an enlarged front cross-sectional view showing a third embodiment of the concave-convex engaging portion in the buffer material molded body for radioactive contaminant geological disposal according to the present invention.

FIG. 5 is a front sectional view showing a conventional example of geological disposal.

[Explanation of symbols]

 A Radioactive contaminant storage body (radioactive substance storage body) 2 Disposal hole 10 Radioactive pollutant geological disposal buffer material molded body (molded body) 11 Body 11a Storage hole 11b Female thread 12 Lid 12a Disk 12b Mating protrusion 12c Male screw portion 13 Concavo-convex engaging portion 14 Disc-shaped joint surface 15 Tapered joint surface 16 Cylindrical joint surface

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Eiichi Asano 3-2-16 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toyosu General Office (72) Inventor Junji Yamagata 3-chome, Toyosu, Koto-ku, Tokyo No. 2-16 Ishikawajima Harima Heavy Industries Co., Ltd. Toyosu General Office (72) Inventor Nobuo Ninomiya 3-15-1, Toyosu Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Technical Research Institute (72) Inventor Susumu Kawakami Koto-ku, Tokyo 3-15 Toyosu Ishikawajima Harima Heavy Industries Ltd. Technical Research Center

Claims (5)

[Claims] 1. A cushioning material used when a radioactive contaminant container (A) is buried in a sealed state, wherein powder such as bentonite is compressed and solidified into a high density state by cold isostatic pressing or the like. The body (11) and the lid (12), which are formed by molding, are combined with each other, and the body (11a) is provided with a storage hole (11a) for loading a radioactive contaminant storage body to be geologically disposed. A cushioning material molded body for geological disposal of radioactive contaminants, characterized in that a concave-convex engaging portion (13) is arranged at a joint portion with the lid. 2. The cushioning material molded body for geological disposal of radioactive contaminants according to claim 1, wherein the body (11) is molded into a bottomed cylindrical body. 3. The body main body (11) in the concave-convex engaging portion (13).
Female threaded portion (11b) formed on the inner peripheral surface of the opening of the storage hole (11a) and a male threaded portion formed on the lid (12) closing the opening of the storage hole and screwed into the female threaded portion ( 12
c) is provided, and the buffer material molded body for geological disposal of radioactive contaminants according to claim 1 or 2. 4. The concavo-convex engaging portion (13) has an annular disc-shaped joint surface (14) and a taper-shaped joint surface (15) connected to the disc-shaped joint surface. The cushioning material molded body for geological disposal of radioactive contaminants according to claim 1, 2 or 3. 5. The concavo-convex engaging portion (13) has a circular disc-shaped joint surface (15) and a cylindrical joint surface (16) connected to the disc-shaped joint surface. The cushioning material molded body for geological disposal of radioactive contaminants according to claim 1, 2 or 3.